PHOTOSYNTHESIS

Now we know where we get our energy from – but where does the glucose come from in the first place? We can trace our supply of glucose back to PLANTS! We either eat plants or eat things that eat plants (the food chain – which we will learn more about later) LIFE is dependent on the availability of an energy source and raw materials used in biochemical processes. So, we know we can make energy – but do we really need O 2 (oxygen) and where does it come from?

Plant Nutrition Photosynthesis – the process of capturing and transforming energy of sunlight into chemical energy Photosynthesis – the process of capturing and transforming energy of sunlight into chemical energy Heterotrophs – can not make their own food, must depend upon plants and animals as a source of food Heterotrophs – can not make their own food, must depend upon plants and animals as a source of food Autotrophs – are capable of making their own food Autotrophs – are capable of making their own food

Autotrophs – are capable of making their own food Phototrophic organisms are photosynthetic organisms or photoautotrophs Phototrophic organisms are photosynthetic organisms or photoautotrophs Use light energy Use light energy

Autotrophs – are capable of making their own food Chemotrophic organisms are chemosynthetic organisms or chemoautotrophs Chemotrophic organisms are chemosynthetic organisms or chemoautotrophs Use chemical energy Use chemical energy Bacteria Bacteria

Light energy Sunlight is called radiation Sunlight is called radiation Travels in waves Travels in waves Sunlight is a mixture of light of different wavelengths Sunlight is a mixture of light of different wavelengths When all wavelengths are reflected off an object, object appears white When all wavelengths are reflected off an object, object appears white When light strikes matter and is absorbed, it increases the atom’s energy level When light strikes matter and is absorbed, it increases the atom’s energy level

The wavelength of the light reflected is the color you see The wavelength of the light reflected is the color you see Shortest wavelength is violet, the longest is red Shortest wavelength is violet, the longest is red A prism will bend the waves and spread out the colors A prism will bend the waves and spread out the colors Violet- blue-green- yellow-orange-red Violet- blue-green- yellow-orange-red

In photosynthesis, the energy absorbed is used to make a chemical bond In photosynthesis, the energy absorbed is used to make a chemical bond A substance that absorbs light is called a pigment A substance that absorbs light is called a pigment

Photosynthetic Pigments Chlorophyll a – directly involved in converting light energy into chemical energy Chlorophyll a – directly involved in converting light energy into chemical energy Chlorophyll b – absorbs light and transfers energy to chlorophyll a Chlorophyll b – absorbs light and transfers energy to chlorophyll a Both absorb red and blue light – reflect green Both absorb red and blue light – reflect green Carotenes (orange) – absorb light and transfer energy to chlorophyll a Carotenes (orange) – absorb light and transfer energy to chlorophyll a Xanthophylls (yellow) - absorb light and transfer energy to chlorophyll a Xanthophylls (yellow) - absorb light and transfer energy to chlorophyll a these pigments absorb light in a different region of the spectrum from chlorophyll a (of different wavelengths) and plants can use light from a wider range of the spectrum these pigments absorb light in a different region of the spectrum from chlorophyll a (of different wavelengths) and plants can use light from a wider range of the spectrum these other pigments (colors) can be seen in the fall when chlorophyll starts to break down these other pigments (colors) can be seen in the fall when chlorophyll starts to break down

Absorption of Light: Chlorophyll a absorbs (uses) primarily __________ light. Chlorophyll a reflects primarily ________ light. blue green

Chromatography: Separates a mixture into its parts by differences in solubility.

Page 15 in your packet: Why Do Leaves Change Color?

The Chloroplasts chloroplasts contain photosynthetic membranes chloroplasts contain photosynthetic membranes chloroplasts are the site of photosynthesis chloroplasts are the site of photosynthesis Page 19 in your packet

A CHLOROPLAST Photosynthetic membranes called thylakoids They are in stacks called grana granum (s) The area in between is called the stroma

THE PROCESS OF PHOTOSYNTHESIS

CONVERSION OF LIGHT ENERGY INTO CHEMICAL ENERGY 6CO H 2 O C 6 H 12 O 6 + 6O 2 + 6H 2 O (light) (this equation represents many reactions that occur in the chloroplasts in the light)

PHOTOSYNTHESIS There are two reactions that make up photosynthesis There are two reactions that make up photosynthesis Light reaction or light dependent reaction Light reaction or light dependent reaction Dark reaction or light independent reaction Dark reaction or light independent reaction

The Light Dependent Reaction reactions that take place only in the presence of light reactions that take place only in the presence of light light supplies energy needed for these reactions light supplies energy needed for these reactions takes place in the grana of the chloroplast takes place in the grana of the chloroplast products are O 2, ATP, and NADPH 2 (high energy molecules used to power the dark reaction) products are O 2, ATP, and NADPH 2 (high energy molecules used to power the dark reaction)

The Light Independent Reaction takes place in the stroma takes place in the stroma CO 2 is used to produce glucose through a process called carbon fixation CO 2 is used to produce glucose through a process called carbon fixation Carbon fixation occurs through a series of reactions called the Calvin cycle Carbon fixation occurs through a series of reactions called the Calvin cycle

Factors Affecting Photosynthesis 1. Light intensity 2. Temperature 3. Water 4. Mineral availability

PHOTOSYNTHESIS

Break it down Page 20 in your packet

Let’s Compare! PHOTOSYNTHSISvs. CELLULAR RESPIRATION

PHOTOSYNTHESIS vs. CELLULAR RESPIRATION RESPIRATIONPHOTOSYNTHESIS LOCATION PURPOSE REACTANTS PRODUCTS ORGANISMS THAT PERFORM IT WHEN IT OCCURS mitochondriachloroplast Change food energy into chemical energy the body can use (ATP) Capture the sun’s energy and change it into food energy C 6 H 12 O 6 + O 2 CO 2 + H 2 O + ATP C 6 H 12 O 6 + O 2 All living cells Green plants All the time Light reaction/day Dark reaction/anytime